Constraints on the Calibration of Borehole Volumetric Strainmeters Using Rayleigh Wave Vertical Seismic Acceleration

Abstract

ABSTRACT To ensure the accuracy and reliability of crustal strain measurements requires in situ sensor calibration. In this study, a seismogeodetic approach for the calibration of volumetric strain is introduced. The protocol, which relies on the dilatational character of Rayleigh waves, combines observational and theoretical analyses based on the near-surface properties of the Rayleigh wave vertical seismic acceleration. The calibration coefficient is estimated for a Rayleigh wave dominant period of 15–20 s using strain data and strong-motion records of acceleration from 62 global events (Mw≥7). The approach shows a good agreement with tidal calibration estimates for a Poisson ratio of 0.22–0.27 and Rayleigh wave phase velocity of 3–4  km·s−1. The protocol is straightforward, it requires no sophisticated simulation but only the numerical comparison of a similarly located accelerometer, and offers an alternative or a complement to tidal calibration.